More Study Needed of Possible Carcinogenesis of Winter Gas Additive

WASHINGTON--Although the chemical MTBE, added to gasoline in thewinter to reduce the emission of carbon monoxide, does not posea substantial human health risk, more study needs to be undertakento assess both short- and long-term health effects, a NationalResearch Council (NRC) committee said in its review of a draftof a federal report.

The federal study assessed the effects of methyl-tertiary-butylether (MTBE) on air and water quality, motor vehicles (fuel economyand engine performance), and public health.

In areas that have not met air quality standards for carbon monoxide,federal law requires the use of additives that increase oxygenlevels in gas during winter months when lower temperatures tendto cause vehicles to emit more carbon monoxide. However, availabledata indicate that oxygenated fuels reduce winter air levels ofcarbon monoxide by as little as 0% to about 10%, the committeesaid.

The NRC committee disagreed with the report's conclusion thatonly a small percentage of the population may be sensitive toMTBE, citing studies showing an increase in health problems amongworkers exposed to MTBE on the job.

In addition, the panel said, cancer estimates for MTBE were basedon animal models and should not be taken as conclusive. The committeerecommended that further investigations be made into MTBE as apotential carcinogen.